1 files changed, 73 insertions, 0 deletions
diff --git a/internal/cli/cmd.go b/internal/cli/cmd.go
new file mode 100644
index 0000000..698cf7c
--- /dev/null
+++ b/internal/cli/cmd.go
@@ -0,0 +1,73 @@
+package cli
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+
+	"github.com/spf13/pflag"
+
+	"tsne.dev/hopper/internal/log"
+)
+
+// Run executes the CLI and returns the process exit code.
+//
+// Note: Help paths will call exit directly.
+func Run(ctx context.Context, args []string) int {
+	main := newMainCommand()
+	err := runCommand(ctx, main, args)
+	if err != nil {
+		var exit exitError
+		if errors.As(err, &exit) {
+			return exit.code
+		}
+
+		var ev errorVerboser
+		if errors.As(err, &ev) {
+			log.Error("%s\n  %s", err.Error(), ev.ErrorVerbose())
+		} else {
+			log.Error(err.Error())
+		}
+		return 1
+	}
+	return 0
+}
+
+type command interface {
+	Usage() string
+	Run(ctx context.Context, args []string) error
+}
+
+func parseFlags(cmd command, flags *pflag.FlagSet, args []string) {
+	err := flags.Parse(args)
+	if err != nil {
+		if errors.Is(err, pflag.ErrHelp) {
+			log.Print(cmd.Usage())
+			os.Exit(0)
+		} else {
+			log.Error("%s\n\n%s", err.Error(), cmd.Usage())
+			os.Exit(2)
+		}
+	}
+}
+
+func runCommand(ctx context.Context, cmd command, args []string) error {
+	err := cmd.Run(ctx, args)
+	if err != nil {
+		var usageErr usageError
+		if errors.As(err, &usageErr) {
+			log.Error("%s\n\n%s", usageErr.msg, cmd.Usage())
+			os.Exit(2)
+		}
+		return err
+	}
+	return nil
+}
+
+func newFlagset(name string) *pflag.FlagSet {
+	fs := pflag.NewFlagSet(name, pflag.ContinueOnError)
+	fs.SetOutput(io.Discard)
+	fs.Usage = func() {}
+	return fs
+}